Alpheus coralvivo, Santos & Terossi & Mantelatto & Torres & Almeida, 2024

Santos, Patricia S., Terossi, Mariana, Mantelatto, Fernando L., Torres, Rodrigo A. & Almeida, Alexandre O., 2024, Morphology and molecular evidence reveal hidden diversity among snapping shrimp of the Alpheus obesomanus group (Decapoda: Alpheidae) with the description of a new species from Brazil, Zootaxa 5474 (3), pp. 225-242 : 229-232

publication ID	https://doi.org/ 10.11646/zootaxa.5474.3.2
publication LSID	lsid:zoobank.org:pub:5D1012F2-7160-4A25-98C5-A9E893FBF39E
DOI	https://doi.org/10.5281/zenodo.12567694
persistent identifier	https://treatment.plazi.org/id/03D98784-8113-5B1B-80E1-11C663EAFE91
treatment provided by	Plazi
scientific name	Alpheus coralvivo
status	sp. nov.

Treatment

Alpheus coralvivo sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Thunor rathbunae View in CoL — Christoffersen 1979: 355 (? possibly A. coralvivo ; see discussion)

Alpheus simus View in CoL — Bezerra & Almeida 2008: 1; Santos et al. 2012: 154, fig. 4B; Soledade & Almeida 2013: 105, fig. 6F; Almeida et al. 2016: 66 (not A. simus Guérin-Méneville, 1855 View in CoL )

Type material. Holotype: female (CL 7.3 mm), Brazil, Bahia, Porto Seguro, Parque Municipal Marinho Recife de Fora , on dead portions of Millepora alcicornis colony, 13.IV.2012, colls. G.M. Reuss Strenzel, G.O. Soledade, P.S. Santos, L.M. Fernandes, I. Matos, MZUSP 36753 View Materials (genetic data MT483210 ) . Paratypes: Rio Grande do Norte — 1 male (CL 2.8 mm, obs. carapace partially damaged), Maxaranguape, Parrachos de Maracajaú , 3–4 m, on M. alcicornis colony, 12.II.2004, coll. T . M. Garcia , MOUFPE 20048 View Materials (previously UESC 995 ) . Bahia — 1 female (CL 6.1 mm), same data as holotype, MZUSP 36754 View Materials ; 1 female (CL 6.5 mm), same data as holotype, MOUFPE 18747 View Materials (genetic data MT483211 ) ; 1 female (CL 6.9 mm), Porto Seguro, Parque Municipal Marinho Recife de Fora , on living portions of M. alcicornis colony, 06. V.2013, colls. G.M. Reuss Strenzel, G.O. Soledade, P.S. Santos, L.M. Fernandes, J.C. Viaggi, MOUFPE 18748 View Materials ; 1 male (CL 4.2 mm), Porto Seguro, Parque Municipal Marinho Recife de Fora , on coral rubble, 06. V .2013, colls. G.M. Reuss Strenzel, G.O. Soledade, P.S. Santos, L.M. Fernandes, J.C. Viaggi, MOUFPE 18749 View Materials (genetic data MT483212 ) ; 1 male (CL 3.9 mm), 1 female (CL 6.6 mm), Santa Cruz Cabrália, Praia de Coroa Vermelha , salinity 36, on dead portions of M. alcicornis colony, 22.III.2011, colls. P.S. Santos, G.O. Soledade, A.O. Almeida, CCDB 7080 View Materials (previously UESC 1411 ) ; 1 female (CL 5.6 mm), Porto Seguro, Praia do Mutá , salinity 40, on dead portions of M. alcicornis colony, 25.IX.2011, colls. P.S. Santos, G.O. Soledade, A.G.L.M. Pedra, MOUFPE 20047 View Materials (previously UESC 1503 ) ; 1 male (CL 4.4 mm), 1 ovigerous female (CL not provided, carapace damaged), Abrolhos Archipelago, Parcel de Paredes , 1982, MNRJ 15400 View Materials ( See Appendix 1 for a list of comparative material) .

Diagnosis. Rostrum and orbital teeth absent. Antennular stylocerite shorter than half length of visible part of first article of antennular peduncle. Antenna unarmed. Scaphocerite, in females, short, rounded distally, reaching distal margin of carpocerite; in males, distally acute, overreaching distal margin of carpocerite. Large gap between cephalothorax and pleuron of first pleonal segment.

Description. Based on female holotype (MZUSP 36753) and male paratype (MOUFPE 18749). Carapace smooth, dorsally convex, unarmed; rostrum absent; ocular hoods dorsally inflated, unarmed, margin between two orbital hoods slightly deep. Eyes well pigmented, completely covered by ocular hoods in dorsal and lateral views ( Fig. 1A–C View FIGURE 1 ).

Pleonal segments smooth; posteroventral margin of pleura 1–5 rounded, sixth pleuron semi-triangular, without articulated plate; large gap between cephalothorax and pleura of first pleonal segment; cardiac notch well-developed ( Fig. 1D View FIGURE 1 ). Telson ( Fig. 1E–F View FIGURE 1 ) tapering distally, proximal region about 4.2 times wider than distal; dorsal spiniform setae absent; dorsal surface of telson bearing one pair of exceedingly spiniform setae, placed slightly closer to lateral margin of telson than to its midline; distal margin of telson narrow and straight, posterolateral angle each with three pairs of spiniform setae; anal tubercles well-developed. Uropods ( Fig. 1E View FIGURE 1 ) with bifid protopods, each lobe ending in rounded tip; exopod slightly longer than endopod; lateral margin of exopod slightly convex proximally and straight distally; diaeresis absent; distolateral margin of exopod with one lateral tooth and one dark-colored spiniform seta overreaching distal margin of exopod, noticeably longer than lateral tooth.

Second antennular article approx. 4 times longer than first and third articles; stylocerite short and rounded distally, not reaching half-length of visible part of first article of antennular peduncle.Antenna unarmed; carpocerite shorter than half length of second article of antennular peduncle; scaphocerite in female short, rounded distally, reaching proximal margin of carpocerite; scaphocerite, in male, elongate, distally acute, overreaching proximal margin of carpocerite; blade absent in both sexes ( Fig. 1A–C View FIGURE 1 ).

Mandible ( Fig. 1G View FIGURE 1 ) with 2-jointed palp; incisor process robust, with 7 distinct teeth, second anterior tooth conspicuously wider and longer than others; molar process flat, with semicircular rows of short setae. First maxilla ( Fig. 1H View FIGURE 1 ) with palp deeply bilobed, inferior lobe bearing 1 slender seta, superior lobe not setose. Second maxilla ( Fig. 1I View FIGURE 1 ) palp well-developed, slender; with upper lacinia cleft, lower lacinia with single lobe; scaphognathite well-developed, with setae around distal and internal edge, tips rounded and lateral margin convex. First maxilliped ( Fig. 1J View FIGURE 1 ) palp approx. 3.5 times longer than wide, tip truncated; two laciniae separated by distinct cleft, exopod well-developed with long flagellum, exopodal lobe poorly developed; epipod about 3 times as long as wide. Second maxilliped ( Fig. 1K View FIGURE 1 ) exopod well-developed, flagellum 3.3 times longer than epipod; epipod about 1.6 times as long as wide. Third maxilliped ( Fig. 1L View FIGURE 1 ) slender, overreaching half-length of second antennal article; ultimate article 1.6 times longer than penultimate, with many transverse rows of stiff setae; antepenultimate article 2.2 times longer than penultimate; exopod overreaching distal end of penultimate article, ending in with long setae; epipod present. Pleurobranch and epipod present from pereiopods 1–4.

First pereiopods very unequal. Major female cheliped ( Fig. 2A, B View FIGURE 2 ) ischium short, stout and unarmed; carpus unarmed, cup-shaped, short, as long as ischium, 5.8 and 6.4 times palm length in female and male, respectively, 2.4 times merus length; cheliped long, approx. 5.7 times as long as dactylus and 3.2 times as long as maximum height; palm gradually narrowing anteriorly; shallow furrow on dorsal surface, mesial and lateral view smooth, with deep furrow on distal third of ventrolateral margins, with distoventral lobe, sometimes denticle ( Fig. 2D View FIGURE 2 ); dactylus strongly bent and hammer-shaped, ending in blunt rounded apex directed down over tip of pollex; pollex half dactylus length, with numerous long and stiff setae on distal margin; cheliped articles free of spines and teeth ( Fig. 2A, B View FIGURE 2 ). Major male cheliped ( Fig. 2C View FIGURE 2 ) similar in shape, but slenderer than female; palm approx. 4.8 times as long as dactylus and 3.7 times as long as maximum height.

Minor cheliped ( Fig. 2E View FIGURE 2 ) ischium short, approx. 1.2 times carpus length; carpus unarmed, cup-shaped, approx. 3 times merus and approx 3.4 times palm length; palm cylindrical, without teeth or grooves, approx. 4 times as long as maximum height; cheliped with slender fingers, approx. 1.5 times palm length; fingertips curved, obscurely biunguiculate ( Fig. 2F View FIGURE 2 ); "balaeniceps" setae absent. Articles free of teeth or spines. Second pereiopod slender ( Fig. 2G View FIGURE 2 ), left conspicuously longer than right; ischium short, approx. 3 times merus length; carpus five-segmented, approx. 4 times longer than chela; segment ratio (proximal to distal): right 2.8: 2.1: 1.2: 1: 1.1 and left 2.3: 2.3: 1.1: 1: 1; fingers approx. 1.3 times palm length.

Third ( Fig. 2H View FIGURE 2 ) and fourth ( Fig. 2J View FIGURE 2 ) pereiopods long, similar in shape and length; ischium, merus and carpus unarmed; merus approx. 1.5 times propodus length, ventrodistal tooth absent; carpus approx. 1.3 times propodus length; propodus approx. 5 times dactylus length, with 4 strong spiniform setae along ventral margin and one pair of spiniform setae at propodo-dactylar articulation; dactylus slender and simple ( Fig. 2I, K View FIGURE 2 ). Fifth pereiopod ( Fig. 2L View FIGURE 2 ) shorter than third and fourth pereiopods; merus 1.1 times propodus length; ischium, merus and carpus unarmed; propodus about 6 times longer than dactylus; with one ventral spiniform setae; distolateral surface with cleaning brush consisting of transverse rows of setae; dactylus similar in shape to that of third and fourth pereiopods; carpus approx. 1.2 times propodus length.

Pleopods with sparse setae on lateral margin of protopod; endopod and exopod with setose edges; male first pleopod reduced. Second pleopod of male with appendix masculina overreaching distal margin of appendix interna.

Morphological variation. Scaphocerite in females presenting two forms: (1) rounded distally, reaching about half length of first article of antennular peduncle, with very reduced blade; (2) rounded distally, shorter than half length of first article of antennular peduncle ( Fig. 1A View FIGURE 1 ). Scaphocerite elongate in males, distally acute, slightly overreaching distal margin of first article of antennular peduncle ( Fig. 1B View FIGURE 1 ) with blade little developed. Number of ventral spiniform setae on propodus of third and fourth pereiopods ranging from 4 to 6 (usually 4). Number of distolateral spiniform setae on uropodal exopod ranging from 1 to 2 (usually 1). Female with smaller and more widely set eyes than male.

Color pattern. Body semi-transparent; some specimens with reddish chromatophores, mainly on cephalothorax ( Fig. 3A View FIGURE 3 ); palm, distal margin of chelipeds and second pereiopod pale yellowish; second pereiopod also showing dark yellow coloration on joints ( Fig. 3B View FIGURE 3 ). Distolateral spiniform setae of the uropodal exopod dark-brown, black or not pigmented.

Type locality. Brazil, Bahia, Porto Seguro, Parque Municipal Marinho do Recife de Fora , 16°24'07.0"S 38°58'55.2"W GoogleMaps .

Distribution. Brazil: Rio Grande do Norte and Bahia.

Ecology. In shallow subtidal reef pools; in crevices on living and dead portions of fire coral ( Millepora alcicornis ) colonies and coral rubble ( Fig. 3A, B View FIGURE 3 ); depth range 1– 12 m.

Etymology. The name refers to the ‘Projeto Coral Vivo’, a project which aims at the conservation and social and environmental sustainability of coral reefs; used as a noun in apposition.

Genetic analyses. The best-fit substitution model selected using the BIC was GTR+I+G, assuming the nucleotide frequencies A = 0.3622, C = 0.2670, G = 0.0996, and T = 0.2712; and the replacement rates AC = 0.0899, AG = 6.8412, AT = 0.2764, CG = 0.3997, CT = 3.6794, and GT = 1. The substitution model variable sites followed a gamma distribution with shape parameter = 0.5590 and invariable sites = 0.4880.

The analysis included species of the A. obesomanus group that are morphologically similar to the new species: A. idiocheles , A. malleodigitus , A. obesomanus , A. saxidomus , and A. simus . The topology obtained in the Bayesian Inference analysis ( Fig. 4 View FIGURE 4 ) clearly separates A. coralvivo sp. nov. specimens from the other analyzed species and indicate a close relation of the new species with A. simus and A. saxidomus . The genetic distance among specimens of the new species was null. The species of Alpheus with the lowest genetic distance values compared to A. coralvivo sp. nov. were A. saxidomus (11.4–12.4%) and A. simus (12.9–14.6%), whereas the species with the highest genetic distance values was A. obesomanus (21.7–23.6%).